Gas treating processes can be very sensitive to contamination by liquid hydrocarbons in the feed gas. An example is amine treatment, such as the Shell Sulfinol process, in which acid gas compounds are removed from a gas stream, in particular a natural gas, by means of an absorption/regeneration cycle. Liquid hydrocarbons increase the foaming tendency in the absorbers, as is known for example from the paper “Texas plant solves foam problems with modified MEA system”, C. R. Pauley, B. A. Perlmutter, Oil & Gas Journal, February 1988, p. 67-70. Foaming leads to insufficient acid gas removal capacity and hence reduced gas throughput. Liquid hydrocarbon quantities as small as 50 ppmv can already have a devastating effect on treating plant performance.
These hydrocarbon contaminants moreover are typically present in small droplets, with diameters in the order of microns and below. Due to their small droplet size and low concentration the liquid contaminants are difficult to remove. Using conventional coalescers, such as a wiremesh, is insufficient to coalesce the majority of the liquid contaminants to a larger droplet size that can be removed by e.g. a centrifugal liquid separator, such as a swirldeck, in an inlet separator to the gas treating plant. So, even high-efficiency separators have difficulties in removing small droplets. One option for removal is to use filter systems, but for sufficient efficiency they need to be very large, they cause a large pressure drop, and are difficult to operate in view of regular exchange of filters and associated safety risks. Fibre bed filters moreover generate a large amount of solid waste
It is an object of the present invention to provide an improved method and device for removing liquid contaminant droplets from a gas stream.